This tutorial should enable you to enable bluetooth audio on Qubes.
You must have bluetooth in your dom0. This may be a pcie device, or a usb device. If it's a usb device, then you need to determine what usb controller owns the device and ensure that it remains in dom0. See WhatIs/SysUsb.
This exposes a (short range) communications path from dom0 to the outside world. The bluetooth stack has had security vulnerabilities in the past, and more cannot be ruled out. If your Security/SecurityModel is in conflicts with this, then do not use bluetooth with Qubes, and disable the device.
So within bluetoothctl you need to search it, then pair
You'll see a line that looks like
Device [mac] Name: [your device]
As bluetooth scans it. (Set the device to rescan)
connect [mac] trust [mac]
Inside bluetoothctl. Then run
Click on the output tab and you should see your device.
Once it's set up, to turn it on again, run
service bluetooth start
To start the service. Your device should then be visible as "dom0".
When using a WhatIs/SysUsb Qube, the bluetooth controller sits inside that VM, isolating it from dom0. The issue then is that the system audio is piped through to pulseaudio in Dom0, not pulseaudio on the USB qube. If we can find a way to do that, that would make this a lot more secure. Let us know if you get this working.